microbial sequences
Environmental DNA was extracted from 0.25 g mixed soil sample using the PowerSoil DNA Isolation Kit (MoBio Laboratories, Carlsbad, California, USA) following the protocol specified by the manufacturer. The 16S region of the bacterial ribosome RNA (rRNA) encoding genes were amplified using a tagged forward primer 515F and a tagged reverse primer 806R for bacteria (Gilbert et al. 2014); and a tagged forward primer ITS1F with a reverse primer ITS4 for fungi (Manter and Vivanco 2007).